The present invention relates to fluorine-containing bisphenols, their preparation, some precursors and intermediates of this preparation, and the use of the fluorine-containing bisphenols as starting materials for the production of liquid crystals, polymers and flame retardants.
Particular fluorine-containing bisphenols are already known as starting materials for the production of liquid crystals (Polym. Mater. Sci. Eng., 1996, 74, 133-134) or as monomers for polymerization (Fluoropolymers, 1999, 1, 127-150), for example for preparing polycarbonate (JP 05170892 A2), polyethers (JP 2000273166 A2), or polyesters (Polymer, 1997, 38, 3669-3676). It is also known that in the case of liquid crystals it is advantageous for these to have a linear molecular structure (C. Weygand, “Chemische Morphologie der Flüssigkeiten”, Handbuch und Jahrbuch der chemischen Physik, Volume 2, section 3c, Leipzig, Akadem. Verlagsges. 1941; H.-G. Elias, Makromoleküle, 5th edition, Volume 1, chapter 20, section 20.1.2, Hüthig & Wepf Verlag, Basle 1990).
J. Gen. Chem. USSR (Engl. Transl.), 1965, 35, 1616-1623, discloses that various 1,2-di(4-halophenyl)tetrachloroethanes (B) can be prepared by cross-coupling of 4-halobenzotrichlorides (A) by means of copper in pyridine. In addition to the desired 1,2-di(4-halophenyl)tetrachloroethanes of the formula (B), this process also gives significant amounts of 1,2-di(4-halophenyl)dichloro-ethylenes of the formula (C). A disadvantage is that these compounds of the formula (C) cannot be fluorinated directly to form the corresponding 1,2-di(4-halophenyl)tetrafluoroethanes, which leads to costly losses in yield.

According to J. Gen. Chem. USSR (Engl. Transl.), 1965, 35, 1616-1623, fluorination of 1,2-di(4-halophenyl)tetrachloroethane of the formula (B) to 1,2-di(4-halophenyl)tetrafluoroethane (C) is possible only by using the highly toxic and expensive antimony(III) fluoride and a catalyst at high temperatures.

U.S. Pat. No. 4,168,388 discloses a process for preparing 2-, 3-, and 4-trifluoromethylphenol from the corresponding 2-, 3-, and 4-trifluoro-methylchlorobenzene. It has the disadvantage that sodium hydride, which ignites readily and reacts vigorously with water, is used as base. In addition, it has been found that the solvent N,N-dimethylacetamide that is used decomposes to form the corrosive N,N-dimethylamine under the reaction conditions described. This prevents recycling of the solvent and makes the process expensive.
Due to the increasing demand for liquid crystals, it is an object of the present invention to provide new fluorine-containing bifunctional compounds having a linear molecular structure.